The Walgreens Boots Alliance Friday said the drug store chain is going private, acquired by private equity company Sycamore Partners in a $23.7 billion deal described as a "definitive agreement."

Walgreens and the private equity firm Sycamore Partners expect to close the take-private deal in the fourth quarter of this year.

Shares of Walgreens Boots Alliance have lost about half their value in the past year, as the chain has faced pressure in its retail and pharmacy businesses.